Binaural loudness gain measured by simple reaction time

Area of Science:

• Auditory Neuroscience
• Psychoacoustics

Background:

• Binaural level differences (BLDs) are crucial for sound localization and perception.
• Previous studies on binaural loudness using scaling or matching methods yielded inconsistent BLDs (2-10 dB).

Purpose of the Study:

• To measure the binaural level difference producing equal reaction time (BLDERT) using a novel reaction time methodology.
• To investigate the influence of hand response laterality on BLDERT.
• To explore BLDERT across the transition from binaural to monaural stimulation.

Main Methods:

• Reaction time (RT) methodology employed to assess auditory perception.
• Participants responded to 1-kHz pure tones (45-85 dB SPL) presented to the right, left, or both ears.
• Experiments included monaural, diotic, and dichotic stimulation conditions.

Main Results:

• A binaural level difference producing equal reaction time (BLDERT) of approximately 5 dB was found for monaural and diotic presentations.
• Ipsilateral responses were faster than contralateral responses, influencing left vs. right ear results.
• Results align with current binaural loudness models.

Conclusions:

• The reaction time methodology provides a reliable measure of binaural processing.
• The findings support existing models of binaural loudness perception.
• Contradicts earlier claims of perfect binaural summation.